Commercially available harvesters retain all the original functions of the first model used to harvest soybeans over 70 years ago (QUICK & BUCHELE, 1978—The Grain Harvesters. St. Joseph. Mich.: ASAE), namely, they cut, collect, transport and thresh the entire plant, separate the grains from the straw, clean and convey the grain to the grain reservoirs. Of these functions, the threshing, which is the system of the harvesters that requires the most energy (KANAFOJSKI & KARWOWSKI, 1976—Agricultural Machines, Theory and Construction, Vol. 2. Springfield, Va.: Foreign Scientific Publications. Warsaw, Poland: Department of the National Center for Scientific Technical and Economic Information. Washington, D.C.: U.S. Department of Commerce, National Technical Information Service) and (HURSMAN, 1983—Optimum cereal harvester operation by means of automatic machine and threshing speed control. PhD diss. Wageningen, The Netherlands: Wageningen University, Department of Agricultural Engineering), mostly uses the tangentially fed bar cylinder and concave system, patented over 200 years ago, and the axial threshing system, patented over 100 years ago. Both systems increase the potential of high levels of mechanical damage to the seeds. Paradoxically, research by HOAG (1972—Properties related to soybeans shatter. Trans. ASAE 15(3): 494-497), QUICK (1974—A quantitative shatter index for soybeans. Experimental Agric. 10(10): 149-158) and MESQUITA (1989—Mechanics of soybean threshing. PhD diss. Lincoln, Neb.: University of Nebraska-Lincoln, Department of Agricultural Engineering) indicated little energy demand for threshing soybean pods. This apparent contradiction was explained by MESQUITA (1989), when concluding that the energy requirement for threshing the entire plant (stalk and pod) was approximately ten times less than that required for merely threshing soybean pods.
On the other hand, if the number of parts of a harvester, and the amount of MOG (Material Other than Grain) processed, are reduced, it is probable that the durability and reliability of the harvester will increase, as well as the quality of the product. Furthermore, this would also lead to a reduction of the required energy input, the size of the harvester and operational costs. According to WOOD (1977—Reliability growth. In Proc. International Grain and Forage Harvesting Conf., 144-145. St. Joseph, Mich.: ASAE) reliability is achieved both by simplification and improvement. He adds that machines built with fewer active parts have greater chances of achieving greater reliability. Based on this premise, new models of harvesters and accessories, having a substantial reduction in the number of moving parts and MOG processing, have been commercially marketed in Europe (VINCENT & MOWITZ, 1987—Farm ideas form around the world. Successful Farming, Des Moines 85(6): 14-17) and (KLINNER et al., 1987—A new concept in combine harvester header. J. Agric. Eng. Res., London 38(1): 37-45). Following this trend, revolutionary prototypes, with 55% less moving parts compared to a conventional harvester, have been developed in the US (RITCHIE, 1995—Mark Underwood's dream machine. Soybean Digest, Hudson 55(6): 8-9). In the same line of research, MESQUITA & HANNA (1993a—Soybean threshing mechanics: I. Frictional rubbing by flat belts. Trans. ASAE 36(2): 275-279; 1993b—Soybean threshing mechanics: II. Impact. Trans. ASAE 36(2): 281-284; 1996—Soybean threshing devices. Applied Eng. in Agric. 12(1): 15-19) and MESQUITA et al. (1997—Blast wheel device for threshing soybeans. Trans. ASAE 40(3): 541-546) have studied the mechanics of soybean threshing based on non-conventional threshing elements or mechanisms and the concept of not extracting the plant in the field. These authors developed experimental equipment to analyze mechanical action by frictional rubbing and by impact of the soybean plants and obtained a threshing efficiency superior to 93% with frictional rubbing, and over 92% and 97% in threshing through impact by moving metal surfaces and by free plastic particles, respectively.
Among the non-conventional elements researched in the problematic harvest of soybeans, air pressure has been the object of several studies. However, in most of this research, it is employed as an auxiliary element, in complement to the main work by mechanical component (NAVE et al., 1972—Combine headers for soybeans. Transactions of the ASAE, 15(4): 632-635; TATE e NAVE, 1973—Air-conveyor header for soybean harvesting. Transactions of the ASAE, 16(1): 37-39; TUNNEL et al., 1973—Reducing soybean header losses with air. Transactions of the ASAE, 16(6): 1020-1023; WAIT et al., 1974—Reducing soybean cutterbar losses with low-pressure airjets. Transactions of the ASAE, 17(5): 817-820; e FAYZ & HANNA, 1979—A pneumatic conveying system for reducing soybean header losses. Transactions of the ASAE, 22(5): 962-964). However, there are no known cases of air being used as the unique element for performing multiple main functions, such as the collection of grains and straw, separation of the grains from the straw, cleaning and transport.
The following brief account of the culture of green soybeans serves to describe a further problem that the new dispositions object of the present utility model solve efficiently, namely, the harvest of green soybeans.
Edamame or green soybean or vegetable soybean is a special type of soybean broadly consumed in Japan, Taiwan, China and Korea, whose importance for human nutrition is rapidly being acknowledged in Western countries as being one of the most healthy foods for the next decades. Originating in eastern Asia, this slightly sweet tasty vegetable has great nutritional value and can be eaten as a starter or as main dish, prepared in many ways. Usually, only the seeds are eaten, and they can be removed from their pods before cooking but, also, the whole pod can be boiled in lightly salted water, so as to facilitate the removal of the seeds. An important food in the Asian diet for centuries, green soybean is one of the most protein rich vegetable cultures, used in China as food and medicine for around 4000 to 5000 years (NGUYEN, 1998—The New Rural Industries. Ed.: K. W. Hyde. Can berra, Rural Industries Research and Development Corporation: 196-203. http://www.rirdc.gov.au/pub/handbook/edamane.html, accessed on Oct. 7, 2001). Practices adopted for the culture of green soybeans are the same for soybeans, except that the green pods are harvested during their green stage, when the pods are almost completely filled by the fully developed grains. According to the Extension Service of WASHINGTON STATE UNIVERSITY (2001—On-farm research: edamane (vegetable soybean) variety trials. Cooperative Extension, WSU, Vancouver Research & Extension Unit. http://agsyst.wsu.edu/edamresearch.html, accessed on Oct. 3, 2001), the consumption of green soybeans in the United States is rapidly rising due to the growth of the Asian-American population as well as the increasing popularity of Oriental restaurants and cooking. For this reason, the extension service of the WSU has worked for five years in cooperation with the Washington State producers so as to select the better varieties for the region as well as those that provide high potential market value.
The high nutritional value of green soybeans, together with high market prices, has promoted a substantial increase in demand and, consequently, farming during this decade, including in countries which are traditional soybean producers (but not of green soybeans), such as the US (major world producer of regular soybeans) and Argentina (main competitor of Brazil, after the US). According to LUMPKIN et al. (1993—Potential new specialty crops from Asia: Azuki bean, edamame soybean, and astragalus. New crops. John Wiley and Sons, Inc., New York, p. 45-51. http://www.ahs.cqu.edu.au/info/science/psg/AsianVeg/Edamame.html, accessed on Oct. 6, 2001), US production is still very reduced, considering the growth in demand and the considerable volume of research of the last 50 years. Unfortunately, Brazil has no commercial green soybean crops and the reduced research is still incipient and limited to genetic improvement, especially at Embrapa Soja (unit of Embrapa—Brazilian Agricultural Research Company), which seeks to achieve size standards for the pods, as well as the nutritional qualities characteristic of the edamame produced in Asian countries. On the other hand, considering Brazil is the second world producer of soybeans and the huge potential market for green soybeans—which is in expansion—, it is believed that the development of this culture is of strategic and social-economic importance, especially for the small and medium sized producers, due to significantly increased production an, mainly, the increase in crop value. According to SHANMUGASUNDARAM et al., (1998—Vegetable soybean for sustainable agriculture. Agric. Improv. Station, Taichung, Special Publication, p. 379-385), the price of the soybeans is US $0.60/Kg, which corresponded to a gross return of US $1,200.00 for a productivity of 2,000 Kg/ha and a production cost of US $1,696.00, which represents losses of US $496.00/ha. However, even with the reduced price of the vegetable soybean pods at US $0.32/Kg, but with an average production of 8,000 Kg/ha, the gross return was US $2,560.00/ha, or a net return of US $884.00/ha. Thus, the gradual decline in the cultivated area of grain soybean over the last years in Taiwan is not surprising, while the cultivated area of vegetable soybean has been increasing gradually by around 10,000 ha during the decade. In an incisive way, the net gain is considerably larger when cultivating green soybean rather then cultivating regular soybean. Thus, green soybean culture is extremely attractive for farmers. Furthermore, SHANMUGASUNDARAM et al. (1989—Vegetable soybeans in the East. In: World Soybean Research Conference IV, Buenos Aires. Proceedings, vol. 4, p. 1979-1986) highlight that, although frozen vegetable soybean consumption is more popular in Japan and Taiwan, there is great potential for vegetable soybean consumption in all developing countries and mainly the poorer countries of Asia and Africa. This could considerably reduce malnutrition related to the low consumption of protein, vitamins and minerals.
While the seeds play a fundamental role in the nutrition of human beings, the residues in the form of stalks with leaves and roots (9 to 15 tons/ha) and empty pods (4.6 to 6.7 tons/ha) are also rich for animal feed or even for the soil, as an organic fertilizer.
Green soybean is harvested after the R6 and before the R7 growing stages (FEHR et al., 1971—Stages of development descriptions for soybeans, Glycine max (L.) Merril. Crop Sci. 11:929-931), while the pod is still green and the seeds are developed in a manner that they fill 80 to 90% of the pod's width (SHANMUGASUNDARAM et al., 1991—Varietal improvement of vegetable soybean in Taiwan. In: Vegetable Soybean Research needs for production and quality improvement: proceedings of a workshop held at Kenting, Taiwan, Apr. 29-May 2, 1991. Asian Vegetable Research and Development Center, Publication N°. 91-346, p. 30-42).
According to SHANMUGASUNDARAM et al. (1998), among the main objectives of the AVRDC (Asian Vegetable Research and Development Center) research programs for vegetable soybeans are developments for adapting the culture to mechanized operations, especially harvesting. During the studies performed up to the present moment, it was estimated that around 76% of the total vegetable soybean biomass is returned to the soil as manure or as animal feed, or is used in both ways. The other 24% of the biomass, composed exclusively by seeds, are used for human nutrition. According to SHANMUGASUNDARAM et al., (1998), as mechanic harvest is probably the major limiting factor of this culture, pod harvesting machines are being experimented. This mechanical harvest intended entirely for pods ensures that all remaining residues of the vegetal soybean plants return to the soil.
The major limiting factor for large scale commercial production, mechanical harvesting has mainly been characterized by the low efficiency of the harvesters used for pod picking. Usually, green soybean should be harvested within 68 to 86 days after seeding, depending on the cultivars and the date of seeding, when around 90% of the pods reach their complete fullness and present a distinctive green color. Green soybean can be harvested three days earlier or later, but, however, the pod productivity can be reduced by an approximately rate of 0.5 ton/ha/day of delay. Since there is no specific harvester for green soybeans as yet, the green bean harvester has provided good performance in green soybean harvesting, removing around 76% of the seeds and separating leaves and stalks. Thus, this harvester operation causes a loss of 24% of the seeds and also damages around 7% of the ones harvested (NGUYEN, 1998). The harvested area and time spent using a harvester for one row of plants is approximately 0.25 ha/hour.
In the Far East, the green pods are usually hand harvested, which is inadequate for the harvesting and processing of green soybean on a commercial scale. According to the INTSOY (1987—INTSOY research focuses on green soybeans as commercial frozen vegetable. International Soybeans Program, Urbana, Newsletter n°. 37, October 1987), the main obstacles to the development of green soybean as a commercial product of major importance are the harvesting problems and the split pods during this operation. While seeking solutions for this problem, the institution adapted and used a self-propelled harvester originally made for harvesting green beans, and concluded that this machine could be used for harvesting green soybean, although adaptations and improvements are necessary. In Taiwan, one of the main producers of vegetable soybean, a harvester is used (FMC), originally intended for harvesting runner beans.
BR MU 7802681-4 (1998) reveals the general concept of the harvester of the present utility model. During the following years, the system continued to be developed by Embrapa Soja and Rota Indústria de Máquinas Agrícolas LTDA.
In 2003, the Revista da Sociedade Brasileira de Engenharia Agrícola (Mesquita et al., 2003—Desenvolvimento de protótipo de concepçcão inovadora de colhedora de soja. Eng. Agric., Jaboticabal 23(1): 129-140) published a study for a harvester with certain technical advances. This prototype has a threshing system of plastic rods where the plants do not need to be cut or extracted from the soil, thus processing a minimum of MOG and a pneumatic system for culling, transporting and separating the grains from the MOG as well as storing the grains. This work evaluated the threshing efficiency and the quantity of MOG remaining on the plant with the new configuration of the plastic impact rods and the first field trials of the pneumatic system for culling, separating, cleaning and transporting the grains. The MOG contained in the samples was compared and quantified, together with the shatter levels of the tegmen, invisible mechanical damage and the physiological quality of the grains harvested, when compared to hand picking and conventional harvesting.
Substantial new dispositions were introduced to this model published in 2003, so the harvester is now technologically ready for use in production.
The 2003 prototype is built in a modular manner for harvesting a single row of soybeans. Initially designed to be coupled to the three-point hitch of a tractor's hydraulic system and driven from its power take-off shaft, the equipment is basically composed of a thresher mechanism which, in accordance with BR MU 7802681-4, threshes the grains directly from the plants in the fields, without cutting or extracting them from the soil, for subsequent collection and processing of the grains. In order to perform this operation, the prototype threshing mechanism was located in a compartment or chamber and used the energy of the impact transmitted to the soybean pods by semi-flexible plastic rods fixed to parallel shafts rotating in opposite directions. This movement causes a sweeping impact of the pods, in an upward movement and to both sides of the plant row which are guided to pass between the shafts while the prototype moved over the crop. The plastic rods are 40 mm long by 3 mm in diameter and are produced by injection as parts comprising three rods disposed symmetrically and radially around a ring having an external diameter of 60 mm and a width of 10 mm further having recessions and projections on its sides. These recessions and projections allow mating the rings when mounting them along the rotating shafts thus forming a sequence of impact rods in a twin spiral configuration. With the rotation of the shafts, these spirals move towards the rear of the prototype, which facilitates the passage of the plant rows when they pass between the said shafts. The present study assessed a different configuration for the impact rods whereby these are disposed tangentially to the rings, rather than in the radial position of the original configuration. It was foreseen that this new configuration would lead to the impact between rods and pods being concentrated to the outer half of the rods which would thus increase their durability, but this was not confirmed.
The shafts are made of steel and are 1500 mm long by 25 mm in diameter, with their centerlines being placed approximately 140 mm apart, and form an angle of 30° with the ground, in a slope descending from the drive pulley to the rear bearing wheel of the equipment. Each shaft is covered by approximately 15° rings totaling 450 plastic impact rods, whereby their ends are tangential the ends of their counterparts on the other shaft. The prototype moved at a speed of approximately 5 kmh−1 and with the shafts turning at around 2600 rpm, this threshing system ensures that all pods are struck at least once by one of the rods.
The pneumatic system of the prototype only used air, through ducts, venturi effect injector valves and air flow regulator valves to perform the remaining operations, namely, separation of the chaff; capture of the grain by differential air pressure on entry by venturi effect injector valve; elevation of the grain by positive air pressure; cleaning of the grains by reduced positive air pressure, eliminating pieces of the pods captured together with the grains; and temporary storage of the grains by diverting the clean grain to the grain reservoir, by reducing the positive pressure and airflow speed generated within the elevation duct. This prototype does not perform the operations of gathering, cutting, transport of the plants at the cutting platform, transfer of the cutting platform to the threshing system, transport for rethreshing, transport to the grain reservoirs, elevation for rethreshing, elevation to the grain reservoir, transport for unloading, shredding the straw, and spreading the straw, which are performed by all conventional harvesters. The reduced number of components of each module allows coupling to the three-point hitch of regular tractors, as well as using the power take-off shaft to drive the twin shafts mounted with the impact rods of the threshing mechanism and the blower of the pneumatic system, which are the only moving components of the prototype.
This is the overall picture of the state of development up until 2003. Work continued and many improvements were achieved, which are scope of the present utility model:                Inversion of the angle of the threshing shafts: this proved a notable change in the concept that provided better results; the parallel shafts mounted with plastic rods now have their lower ends close to the ground towards the front, in relation to the direction of the harvester's movement, in a manner that the said shafts form an angle greater than 90° and less than 180° in relation to the ground, or, in other words, the action of the shafts occurs from bottom to top in relation to the plant.        The rings, that were formerly fitted with three rods (120° between each rod), are now fitted with six flexible cords (60° between each cord).        There is a new method for the mounting the flexible cords to the rings;        A pneumatic system was added for preventing the loss of grains;        An inertial chamber was added for the final separation of chaff;        Outlets for expelling chaff;        Lateral hitch to the tractor, where formerly this was directly to the tractor's three-point hitch, with a capacity for up to three thresher modules;        A light self-propelled harvester was developed equipped with thresher modules arrayed under the chassis;        Plant extractor prior to threshing by the twin shafts mounted with impact rods for cultures such as beans (Phaseolus vulgaris L.);        Separator system for grain pods;        Semicircular casing around the lower and final section of the shafts, to allow the plants to slide past, fitted to the system for harvesting rice and wheat with the descending thresher shaft system;        Semicircular casing around the shafts, at the entry of the machine protecting the stalks of the plants from the action of the flexible cords and thus only threshing the upper part of the plants, for harvesting rice and wheat with the ascending thresher shaft system;        Defoliant roller for harvesting green soybeans.        
Thus, the harvester object of the present utility model presents a specific variation for harvesting green soybeans, furthermore, and has demonstrated a relatively good performance in harvesting the pods. The first component of this harvester to come into contact with the crop is a cylindrical bristle brush positioned transversally to the direction of movement having the purpose of stripping the greatest possible quantity of green leaves from the plant, which is the latest advance on the list of improvements, namely, defoliant roller for the harvest of green soybeans. This initial operation facilitates the subsequent removal of the green soybean pods, pulling them from leafless stalks.
Other researcher's attempts for harvesting green soybean, MILES & CHEN (2000—Edamame harvest trials. WSU Vancouver Research and Extension Unit, Vancouver, Report, 8p. http://www.agsyst.wsu.edu/EdamameReport2000.pdf, accessed on Oct. 16, 2001) proved the low efficiency of mechanical harvesting, as only 50% of the commercial crop in Washington State was harvested, despite using the cultivar which offered the greatest height level of pod growth in relation to the ground, one of the best characteristics for mechanical harvesting. Thus, they concluded that improvement in harvesters is fundamental for achieving greater harvest efficiency and for making the culture of edamame feasible on a commercial scale.